Octatonic

February 10, 2017

Here is short piece using one of the more common octatonic (eight-tone) scales. This particular octatonic scale is often referred to as the diminished scale. It can be described as a symmetrical scale consisting of alternating whole and half-steps.

The scale I used in this piece is as follows:

A B C D Eb F Gb Ab

Of course you could also consider this scale as alternating half and whole-steps by simply starting on the second degree.

There are a couple of ways of looking at this scale and its construction that may aid in learning this scale on the guitar.

Personally I like to think of it as the first four notes (tetrachord) of two minor scales a tritone apart:

A minor: A B C D plus Eb minor: Eb F Gb Ab

You can also think of it as the combination of two diminished seventh chords a whole-step apart:

This scale generates many new sonorities as well as familiar ones but in a context that is definitely not tonal as we know it. It was an interesting exploration of new sound combinations and has helped me become more aware of the use of this scale in contemporary composition. Hope you enjoy it and gain some new insights into contemporary compositional techniques. I have included this piece in the "Seasons" collection as Summer.

Notice how the pattern of triad types repeats at the interval of a minor third. This will be the case for all tertian constructions as we add sevenths:

Adim7 B7 Bm7 Cdim7 D7 Dm7 Ebdim7 F7 Fm7 Gbdim7 Ab7 Abm7

When we add ninths, the minor seventh chords become minor seven flat-nine (not such a great sound so not very useful).

When we extend the dominant seventh chords we find the additional tones create all of the traditional altered dominant sounds with the exception of the 7#5.

For example, B7 can become B7(b9)(#9)(b5) or any other combination of these additional altered tones. This will be the case for all the other dominant seventh chords within the scale which occur a minor third apart.

In the context of jazz improvisation it can be seen that this is an excellent scale for altered dominants. Not quite as good as the altered dominant scale (seventh mode of melodic minor) which contains all the altered tones (b9 #9 b5 #5) as well as the root, third and seventh of the altered dominant chord.

When thirteenths are added to the dominant seventh chords we find the most interesting 13(b9) harmony is created. I personally really like this chord sound and the octatonic (diminished) scale is an excellent choice when soloing over this harmony.

One last point of interest. There are only three different forms of this scale due to its symmetrical structure. The three forms are a minor second apart and would again repeat at minor third intervals as do the chords:

A B C D Eb F Gb Ab

Bb C Db Eb E F# G A

B C# D E F G Ab Bb

I hope this gives some additional insight into the diminished scale and its harmonic and melodic possibilities.

Comments

February 10, 2017 @02:35 pm

Rhoderick

Thank you John, a very atmospheric piece. I love it. Thanks again.

February 10, 2017 @01:40 pm

Jim Sica

John, was listening to your "Influences". Just beautiful I loved it. Just wanted to share and hope your doing as well as your playing and composing! Best, Jim